The distance from city C to city D is 4,814 miles.
The answer to this is is 1.37. You add all of them and divide by 3.
All triangles have a total of 180° in them.
So to find x, simply take 50° and 100° from 180°:
x = 180 - 100 - 50
= 30°
So x = 30°, and thus option D